So I have 1980 2wd yota and I will go to start the truck in the morning when its cold out and I turn the key once and the temperature gauge shoots to instantly hot.. Is this bad sending unit? How can I find the sending unit its a 20r engine. Please help me

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Thanks guys Fixed the problem love knowing my temp now

 

I have fixed a couple of the sending units just by getting the green gunk off of it. I just use a green scrubby pad or brass wire brush.

 

So it is a bad sending unit? Cause the needle goes straight to the top when warming the truck.. Also could this be the reason why I have bad gas mileage only getting 16-18 mpg 201miles on 11 gallon tank?

 

Well 16-18 is normal for a carbed 4 cyl motor. Your temp sender is probably junk. Toss it and buy a new one.

 

okay well sender is easy fix right just unbolt it, bolt the new one and plug the wire back in correct?

 

Dope the threads or you will be sorry.

 

And in case you don't understand that jargon:

Wrap the theads in teflon tape.

 

so pretty much lock tight correct?

 

Hope you didn't use locktite. poew130 meant plumbers white teflon tape. I think plumbers putty or "pipe dope" would be better or maybe even dielectric grease so the sender can make contact with the engine block. The sending unit varies the amount of ground or resistance to ground to tell the gauge what the engine temp is. If there is no contact between it and the block, there's no "ground" or total resistance = a cold/hot engine depending on how that sensor is setup.

 

Well i didn't use locktite I used Teflon tape

 

Your wire is grounding out some where. It's touching a metal part!!

 

I've heard that JB Weld is a good thread sealer.

 

I have fixed this issue it works no bad ground just bad sensor